In the next funding peroid, we will continue to use modern neurtoanatomical methods to analyze, in significant detail, the organization of extrageniculate visual pathways in mammals. Cats, monkeys, and rats will be primary experimental animals; however, other animals may be used for comparative studies. Specifically, the major thrust of our research endeavors will focus upon defining the basic connections of the pretectal complex. Thus, we are presently engaged in defining the efferent systems of the complex especially with regard to brainstem and thalamic oculomotor centers. Concurrently, we are also examining the neurotransmitters localized within pretectal neurons and/or terminals within the complex by use of immunoreactivity to specific compounds. To date, we have used the presence of acetylcholinesterase and glutamic acid decarboxylase immunoreactivity to identify pretectal systems which may use cholinergic and gamma-aminobutyric acid transmitters, respectively. We plan to extend the transmitter studies to include an analysis of enkephalin, dynorphin, and somatostatin immunoreactivity within the pretectal complex. Double label experiments will also be conducted in order to relate these neurotransmitters with specific afferent and efferent systems. I also plan to continue to study the connections of visual centers which are closely related to the pretectal complex. Such areas include the retina, the superior colliculus, regions of the neocortex, the lateral posterior nucleus of the thalamus, and certain cranial nerve nuclei which receive an input from the pretectum. Detailed data regarding important midbrain visual centers such as the pretectum will, in turn, reveal something about their role in vision as well as overall brain function.